If you were signer user, you can migrate your account to wallet. The migration process is very simple. You just need to install the wallet extension and follow the instruction.
You can view Manta Signer Account's Phrase by click the app icon on right corner.
Next you will need to copy the Secret Recovery Phrase.
After that you can import account to Manta Wallet from the browser extension.
Paste the phrase from Manta Signer and waiting for your account's import to be finished.
For the first time you need to sync zkAssets manually.
And after the sync is finished. You can switch to see zkAsset's balance and starting to use it.