Salesforce Apex Trigger: Share Opportunity files with parent Account

I am looking for a talented developer to create (or fix an existing) Salesforce Apex Trigger that will automatically share Opportunity Files with parent Accounts. An attempt has been made in a sandbox using the following guide as a basis (https://sfdclesson.com/2020/04/25/how-to-upload-share-a-file-across-multiple-records/) but it has not been successful.

The developer can attempt to debug and fix the existing attempt or provide their own solution.

I've uploaded the attempted trigger and class for reference.