Thanks for the update. If you have access to the Meraki Client VPN page, you can download Secure client from there:
Honor system is for Secure licenses. As you can see from the top of the picture, you can just turn it on and go. There isn't a check to make sure you have the required licenses for Secure client yet.
Salesmen are always very responsive until they get the sale 🙂
As for the SMB speeds, there are too many variables to say on that one. It could be MTU settings, platform settings and so on. If you are getting the proper speeds via other protocols over Secure Client, then you know the platform and end devices are capable. I would suggest doing a packet capture (no im not Meraki support lol) to make sure you are not getting a bunch of retransmissions, or fragmentation for SMB. I do not have MPLS on my end, but my MX hooks directly into a MS aggregation switch (10gbps) into a access switch via 10gbps with all clients connecting at 1gbps and I get the speeds I mentioned above.
Again, you have to take into account the speed of the end user (the vpn users internet connection), your head end internet connection. Overhead for IPS/AMP/URL etc. Im assuming that you get full speed internally, its just over the vpn that its slow? If so, then its something going on with MTU etc which a packet capture from the remote vpn user, and the server hosting SMB should tell you where the problem is. Im assuming you are using Windows Server for SMB shares
https://learn.microsoft.com/en-us/troubleshoot/windows-server/networking/slow-smb-file-transfer
https://community.cisco.com/t5/security-knowledge-base/anyconnect-mtu/ta-p/3150017
https://www.reddit.com/r/sysadmin/comments/2mt3jc/reducing_mtu_value_to_fix_slow_cifssmb_over_vpn/
Hopefully this helps!