If you used Turbo Tax last you should be transferring from the Turbo Tax return. If you used the installed program for 2023 you transfer from the file ending in .tax2023.
Is .tt23 a HR Block file? Not sure if you can transfer it into the Online version.
Transfer into the Online version
https://ttlc.intuit.com/community/entering-importing/help/how-do-i-transfer-last-year-s-return-into-...
