If your tablet works like my MiniBook x N100 then you should use a power bank that supports USB C Power delivery and is able to provide 20 Volts.
What are the specifications of the power bank you tested? If the output has a USB A socket then won’t work. If it has a USB C socket and it can only deliver 5 Volts, it won’t work either.
1 There are no voltage specifications on the Amazon website so it may not deliver the voltage required by your tablet.
2 This power bank is advertised as a power bank for phones, and not for tablets or laptops. That is an indication it cannot deliver high voltages.
Look for a Power Bank that can deliver 5, 12, and 20 volts. Don’t buy one without these specifications.