It seems that you have a concern for communication between the client and the server, but the certificate may not be the cause ...
Did you open port 443 on the Debian server (login in https by default) ?
In the same way, the address of the server ("Server =" ...) in the file ocsinventory.ini does not include a port (??) so connecting by default to 80 port, your correct syntax would be:
Server = https://192.168.10.64:443/ocsinventory
Try this and do not forget to stop on your Windows client the "OCS Inventory Service" before modifying the ocsinventory.ini file then restart service.
Personally, the blog of Milos Zengel is a good approach for the installation of the OCS Inventory server but can be improved (not perfect on the https part)...