When you launch PAI Up for the first time, you will be given the option to create a new wallet or to recover a wallet. If you have a 12 word recovery phrase from a previous wallet that you would like to import, select recover wallet and then enter the phrase. After that has completed, the wallet will need to sync in order to collect all the information it needs about your balance. Initial syncing can take many hours so please prepare to leave the app open for an extended period of time.
If you wish to import a wallet using a recovery phrase but you already have an active account in PAI Up, you will need to follow the directions to wipe the wallet before beginning the process above. If the wallet you are wiping has funds, be sure to write down the 12 word recovery phrase for the existing wallet (which can be found in the Security Center) before loading the recovery phrase for the wallet you wish to import.