Choosing an external laptop battery?

Question

Batteries

Once again, left without light and, soon, without a battery charge, I decided to purchase an external battery. For a long time I wanted to buy an autonomous charger for mobile devices, and, as it turned out, there are also those for laptops.
I don't know much about electronics at all. The PSU says that the outgoing current is 4.74A, 19V. But, most external batteries support 3.5A. To be precise, this model caught my eye: www.ebay.com/itm/Veho-VCC-A010-PROXT-Pebble-Pro-Po...
As a rule, in the description of the battery model it is not written which laptops are supported ( what connectors are included.
Therefore, I have two questions.
1. What is the risk of connecting a charger with a different current strength (in this case, somewhat less)
2. If there is no connector for my laptop in the kit (I have Asus K53TA-SX222D), is it easy to find an adapter in offline stores (for example, Aser → Asus)?
Thank you.