I don't think you can install SOLMAN on shared SQL DB cluster along with non-sap applications are supported.
Please refer to note
The mentioned SAP note says that if you buy the full license directly from Microsoft, from a license point of view, the database can be used for all purposes. Non-SAP usage database can be added to the MSSQL Server Instance.
From the instance management perspective, probably using a dedicated instance can be more useful, but in this case you will need more computer resources, because you will have 2 MSSQL instances running simultaneously instead of just one.