How do I keep my plants alive?

I have tried keeping plants in my aquarium multiple times but they always seem to die. For the past year, I have only kept some anubias and crypto's. The anubias seemed to do fine but they have developed brown spots over time. Two months ago I trimmed all the bad leaves in the hope that it would disappear. It didn't. There are slowly new leaves forming but unfortunately they also have the brown spots. The crypto's have been in the aquarium for two years but they don't really seem to grow. They also don't have a lot of colours.

I wanted to give some other plants another try, just to see if I can do it this time.

I bought the following plants:
- Three echinodorus bleheri
- Two cryptocoryne wendtii

I was always running two Juwel T8 Day-light lamps. Three days ago I bought a Juwel T5 Nature light. Currently I am running one T8 Day-light lamp and one T5 Nature light. They are on 5,5 hours a day. I also started adding EasyLife EasyCarbo every day, EasyLife Profito once a weak and Dennerle E15 Feractiv every two weeks. Besides that I have also added EasyLife Rootsticks to every plant. I am not adding CO2 to the tank as that is way to expensive

Long story short, I have some questions.
- Am I adding the right nutrients?
- Are my lights on long enough?
- Did I plant the new plants correctly
- What is causing the brown spots on my anubias?
- Are there things that I should to different?
- Tips and tricks because I suck at keeping plants alive

Thank you in advance! Hope I am not asking to many questions or looking stupid.

Here are some pictures of the anubias







Here are some pictures of the old crypto's





Here are some pictures of the new plants












Fun fact
I am a gardner and somehow I suck at keeping aquatic plants alive

 

CO2 not as expensive as you think - initial outlay may be high to get the right regulator and piping etc - maybe 150 euro - but if you get the right kit you can then use cheap CO2 from fire extinguishers where the CO2 works out at about 0.3 euro per 40litres aquarium per six months (eg a 2kg extinguisher lasts us 6 months in a 120l and only costs a tenner). Better than your fish too than liquid carbon which is gluteraldehyde - an industrial strength sterilizing agent used in hospitals :/

 

co2 is super cheap . except the start up is a little steap. i bought a regulator at co2art.us website and i bought a 5lb co2 cylinder locally so around 200+ dollars . get your co2 lining and diffuser(i bought the bazooka on co2art) but as far as upkeep a refill of co2 here for 5lb is 21 bucks but its been 2 months since i started it up and its not even close to empty. from what ive told you pretty much only have to refill it once a year depending on usage i guess obviously. but its a good investment imo even though i suck at plants still

avoid the fluval co2 kit . just a rip off youll have to buy a 3 pack of cartridges like every month and the pack costs about 50 bucks

Aquarium CO2 System Specialists | Diffusers, Regulator CO2 systems if you wish

 

Both replies suggest getting CO2. I will take a look at it. However, are the lights that I am using right? There is no real point in getting CO2 if the other factors are bad. I am also not using a nutriënt rich substrait. Won’t that be a problem if I add CO2.

Anyone that can answer some of the question I asked in my first post?

 

There is no real point in getting CO2 if the other factors are bad.

100% correct
Your fertilizers don't have NPK macros. Since you're in Europe, try Aquascaper Liquid Plant Food or Tropica Specialised. Could also get the nutrients individually and formulate your own routine, but that might be more complicated than you would like.

5.5 hours is fine, you can try 6 if you'd like, I would not go over 8.

Plants look planted fine, make sure the crowns of the echinodorus and crypts are not too deep

The spots on the Anubias are algae, and so is the black border around the edges of the leaves. To me this looks like a milder case of brush algae.
Take a look at this:
How to get rid of Black Beard Algae (BBA)
^The whole website is a great resource for improving your planted tank knowledge/skills

Unfortunately it's hard to judge a light without PAR data. See if this calculator helps you:
https://rotalabutterfly.com/light-calculator.php