You gotta use your Plarium ID.

This is a weird situation.  That is my exact reddit post, copied here for some reason.

Here is the edit that I made to the post, a few hours later.

    Edit: Here's how you get it to actually work. 

• Put in your Google account email address
• Try a password
• Password fails, click "Forgot Password"
• Open link in your email to "Reset Password"
• Create new password for the Plarium account
• Return to application and enter new password 

    Since I had never made a Plarium account prior to this, it is not clear to me what password was originally on file for the account. 

Now that I have actually tried playing the game on Plarium Play, I can say with some certainty that it, in fact, does not work.  Even after creating a Plarium account and linking.

I downloaded the game and started it, and it put me in the new player tutorial.  After playing through the asinine requisite bot games to actually access things like my in-game profile settings, there is no way to recover my original account data through the new client.  It simply does not allow me to try to link the Plarium account to my Google account in-game.

It's not clear to me why this would even be necessary, since within the Plarium Play launcher, the accounts are displayed as linked.  Sadly, linking the accounts does not seem to actually accomplish anything of meaning.

Allow me to link the original reddit thread.  Note the similarity in account names.

Hello guys! 

In order to maintain cross progress between the mobile and desktop devices, you need to use Plarium ID connection only. Please make sure you follow the steps described in this instruction: https://plrm.me/3zMA2Ip

However, if you still have difficulty connecting the devices, please contact our support agents via this link: https://plrm.me/arena_support or email them at: arena.support@plarium.com. They will help you!

actually got it to work completely just made a new plarium id logged in via mobile and done. could use my mobile account on pc fine. to bad nothing has been added to make me care to come back and actually play

I got it to work just fine, apart from the fact I'm really bad at using the keyboard. So since there is no gamepad support on Plarium Play its pretty useless to me, back to the tablet I suppose. it's a pity because it looks great on a 32 inch screen.

Thank you very much for your feedback! The support of an external controller for Mech Arena's desktop version is already in the works 🤗 Hopefully once it is out, you'll enjoy the PC version to its fullest.