You need Volunteers for Salesforce version 3.105 or above for V4S Mobile installation. If you don't find 3.105 or above version of VFS on the AppExchange, please click here to download/upgrade VFS to the latest version.
Please login to your Salesforce instance with an ID that has Administrator privileges. Upgrade Volunteers for Salesforce to version 3.105 or above. Then install the latest version of V4S Mobile from the AppExchange.
The latest version of Volunteers for Salesforce is on Github. Click here and follow the instructions from the "Install the V4S Stand-alone Package" in the Setup and Configuration Guide.