The order was created without any issues so you may have some issues with your Electreum setting.
The problem is probably with the base unit. The base unit has been set to mBTC and OP is entreating the amount in BTC.
Basically, yes, you can transfer any amount you want from one wallet to another.
This is not accurate. You can't make a transaction creating an output which is smaller than the dust limit.
As I said in my previous post, the dust limit is 546 satoshi for legacy addresses and 294 satoshi for native segwit addresses.