UBR-LTE Bonding Subscription questions

I’m looking for clarity. I have a UBR-LTE that is out of warranty/PrimeCare. I would like to blow the dust off and use it for a bonded mobile connection a few times a year. But it’s not clear to me what is required and how much this would cost.

From the UI of the UBR-LTE there is a link to the peplink website where I can sign up for a subscription to SpeedFusion Cloud. For instance, the plan B is $20 for a 180 day, 500GB plan. Do I also need to have a PrimeCare sub for this to work with bonding (SpeedFusion)?
Conversely, I’ve been planning to install FusionHub Solo on a VPS and was hoping to use that for my bonded connection with the UBR. But, do I need a PrimeCare sub for that to work?
Can someone clarify the options and costs involved?