1. PHP REQUIREMENT LINK : https://docs.clientexec.com/en/article/system-requirements-yl750s/ (7.4 min requirement is mentioned in 6.7.0 changelog)
2. Keep the "Default Payment Type Attributes" value as it is in setting table.
3. Keep the default entries in tld_extra_attributes table as it contains generalised data. Check with base64_decode('value');
4. [NA]6.2.x does not work with MySQL 8.0. It will be supported after 6.3.x release. Enable it once 6.3 is released. 