Cannot restore data using Postgres WAL files
You need to read up on how backup and recovery works. WAL doesn't let you go backwards in time, only forwards.
When restoring you would normally restore your data files from your backup (eg one taken with pg_basebackup). That will get you back to the moment the backup was started. If you want to go further in time, you need to supply the WAL files for changes made since the backup. In your recovery_conf you can specify to restore to the time just before the table was dropped using recovert_target_time =  as you have done.
Normally such a restore would be done in a secondary environment. You would then export the dropped table(s) or modified data and import that into your production database (or run update/insert/delete statements to change the state of the database). That way you don't lose other modifications made since the table was dropped.