Confused on linking PC/Steam/PS4

My main account is PS4, and i understand there may be some issues with possible linking my newly started PC account. But 1st question. I didn't know there was a website downloadable for the game, since I just started an account on steam. But having severe crashing and stalling issues from Steam client, so wanting to see if same issue happens with POE website download.

So, how do I merge all of these systems together? If POE2 is only way to merge these minor microtransaction Steam acct, just this leagues item. Is there a way to move this to my PS account too? My PS needs to be sent into Playstation due to bad hard drive, and will likely take 2 more months, so won't be able to redo Necro league for the microtransaction again, so this is on my Steam client account.

But do I also need to register an email for PC version game and cannot pull steam over? Or Playstation over?

I can only play controller anyway as cant figure out mouse & keyboard at all

Thank you