cacique

You can't download 4.7.3 anymore. You must update it directly into 4.7.4.
Import from old? 🙂 You can run just admin/upgrade/ and it will take care of everything. 🙂

You will not need to go version by version to upgrade our software. Just run the 4.7.4 to upgrade and it will do anything it needs to 🙂 .
As you are going from a version that does not support PHP 8, I would recommend doing a manual upgrade so you can get your server all ready from the PHP upgrade and then perform the Invision Community upgrade.
NOTE: Prior to upgrading, you will want to explore any third party applications/plugins/themes/etc... you have installed and uninstall the ones which are not compatible with 4.7 and are never going to be. I would advise disabling all these and switching to an unmodified theme as you are performing a good jump in versions.

Hi @cacique,
If you encounter any issues during your upgrade, please don't hesitate to get back in touch with us for assistance.

+1 for a better documentation in offical docs for Rewrite Rules on nginx.