Spamalia73 you can play on pc with the portal website. Still have some advantages over mobile like use of decorations and larger screen giving more oversight over maps. If your game on tablet is connected to a google account then use those details to login. If you are unable to login on the Portal with those details start a new portal game. Write down both ID numbers and send a ticket to support asking them to connect the accounts.
General advise : write down your player ID number now so if anything ever goes wrong the account can be restored !