From the logs you have supplied, I can see what is happening, but I’m not sure why. Hopefully you can help with that.
When the Octopus service starts, it checks the database to see if it needs to be updated. It does this by checking the SchemaVersions table. In your case, it can’t find the SchemaVersions table, so it assumes it is a brand new database, and is attempting to run SQL scripts to create the required tables, stored-procs, etc. But apparently these already exist, so obviously this script has run before.
Could you inspect the SQL Server database Octopus Deploy is using, and see if a table called SchemaVersions exists?
If it does, then perhaps there is a permissions issue? If this is the case, we can investigate further.
If it does not exist, then I suspect something failed at some point, and the database is now in an invalid state. Deleting the database and installing Octopus again will probably be the best option in this case.