If you want to deploy on another system with a version of PHP 7.4x, it shouldn’t be difficult provided you can get a full extract of your existing database. You can create a new database on the new system, upload the extracted contact. You will need to download the master_2019.2 version. Make sure this is the version you down load. It needs to be used to update the database content before you can change to the master_2020 version. You will need to update the information in the config/config.php file for the database. You can get this info from the config/config.ini file on your existing system, It might be necessary to enclose the database password in double quotes if it has special characters.
Once this setup is in place you can access SI from your browser. If it is set up correctly for database access, you will get the update screen that shows you a list of updates to apply. If not set up correctly, you will get a message that you need to create your database. In this case, check the settings in config/config.php file and try again.
The master_2019.2 update is important. It contains a change to add foreign key support to the database. All updates prior to this one will apply but the foreign key update can stop if it encounters orphaned records. This situation needs to be handled on a case by case basis.
For example, one user had multiple domain ID’s in his setup and this caused the the update to stop reporting records with orphaned ID’s. Other examples are orphaned si_invoice_items records or orphaned si_cron or si_cron_log records. The domain required the missing domain record to be added to the si_user_domain table. The later issues probably need to orphaned records to be deleted. Whatever is required, you need to address the issues and then access SI again so the update process completes.
Once he master_2019.2 update completes, you can update to master_2020. You can get all the needed update information via the Version Update Process link on the left menu.
Hope this all works out for you.