The last time I onboarded someone I tried to make it really simple.
With Keys I said, export your keys, take a copy of the export and save it somewhere different. Get your posting key and login with that. Forget the rest for the moment.
Then I said, write a post, max once a day at first try to get your tags right by looking at other posts similar and follow some folk from my feed and more if you can find them. I mentioned how important it was to source images or use free ones and NOT to copy stuff from other places
I introduced the active key later.
It worked for a while but yeah, the whole thing is a shitshow for the average user who just wants to post and have fun