That company has 10s 36v, 13s 48v, and 14s 52v battery holders for 18650 cells.
The battery holders can stack up to make 2p, 3p, 4p, etc batteries.
That is a very interesting concept. If a cell goes bad in say a 13s stack, you just replace the one cell, no spot welding.
I did a 15.3 mile ride the other day and averaged 2.7 amps, using my 13s 4p battery, each series group would be providing about 0.7 amps. That should be well within the capabilities of these battery holders. The holders use a 15A fuse and charge is recommended to be limited to 2A when charging the holder as a unit.
There would be no BMS, occasional balancing would be done by individually charging each battery holder unit.
For low power applications this should work, but it might not be cheaper than buying a pre-made ebike battery on ebay or Amazon.