Is the APFS drive the internal system drive of your Mac? If so, the password of it is your admin account PIN. Try to unlock it with the login password, after accessing the drive, you can use professional Mac data recovery software to recover deleted data from the APFS drive, under the condition that it's not trimmed yet.
The system drive of your Mac is most likely to be an APFS-formatted SSD. In this case, unless you've enabled other encryption on it such as FileVault, the password to access the drive is your admin account password. After you enter the SSD, since it's TRIM-enabled and you've emptied the Trash, it's almost impossible to recover data from SSD on Mac. Here's why:
Unlike HDDs, SSDs have a feature called TRIM, a command that stands for Advanced Technology Attachment (ATA). In most cases, TRIM is enabled by default on SSDs. If a file on the SSD is deleted permanently, the data will be wiped out the next time your Mac prepares the sector for usage. It will be far more challenging to retrieve deleted files from a MacBook SSD if this functionality is enabled.
However, you still have a chance to restore your data. Choosing a reliable Mac data recovery tool becomes vitally important now. We highly recommend you use iBoysoft Data Recovery for Mac, one powerful and competent SSD recovery tool. With it, you have the opportunity to restore deleted data from SSD on Mac. Free download it by clicking the button below.
Let's get back to the topic again. The solution above is based on the assumption that your drive is the internal SSD. However, if you are using an external APFS-formatted drive, you won't be able to access an APFS-encrypted drive without the correct password, not to mention to recover files from APFS drives.