Mass Effect 3 online pass key error

its been almost 3 years now since ive been trying to play mass effect 3 multiplayer and every time i download it again because i hope things are fixed im met with the same error when i click the multiplayer option. Error online pass key is needed to play multiplayer.
where i can find this i have no clue ive searched the EA app for it ive tried searching online how to get it, im running in to a brick wall here... i bought this game many years ago and when it was owned by Origin i was able to play online happily now since the change of ownership im unable to play online and i have extreme difficulty in finding a way to even purchase an online pass key so that i can play multiplayer. 

i know ill be told by people to troubleshoot the issue, beleive me i did this all to many times. i have fiber internet 300upload 300download and even whilst i right this im having two games running plus streams running on twitch , i have a very good computer i need to have one and good internet because im a streamer on twitch. so my computer or internet is not the issue.. the issue is finding a way to purchase the online pass key which i cant find anywhere.

can i have someone tell me please.

thanks in advance