Get a SAP server access: https://www.michaelmanagement.com/sap-access.asp?aid=107112&utm_source=ytb
Read the full walkthrough: https://www.newsaperp.com/en/blog-saplogon-add-server-sap-750
To access a SAP application server, and use the SAP GUI or FIORI interface, the first step is to proceed to download SAP logon 750, then continue with the corresponding SAP 750 installation, and then configure one or more SAP application server, either manually as explained below, or by using an existing SAP LOGON server list - and finally personalizing the interface: change SAP language or change SAP theme for example.
Each of the SAP servers configures will represent a different instance of SAP to which you will connected, generally each of them representing a different environement, such as developement, business validation, and production, and different for each of the company's business unit.
Every single SAP application server has its own database, set of data, and customized programs. They can be replicated and exist on each of the SAP servers, or be different on every one of them.
See below how to add manually a new connection in the SAP LOGON server list displayed in the SAP GUI interface: https://www.newsaperp.com/en/blog-saplogon-add-server-sap-750