You can’t sacrifice a Junk token to pay multiple costs. For example, you can’t sacrifice a Junk token to activate its own ability and also to activate the second ability of Junk Jet.

You pay all costs and follow all normal timing rules for the card played from exile with a Junk token’s ability. For example, if the exiled card is a land card, you may play it only during your main phase while the stack is empty.

Some spells and abilities that create Junk tokens may require targets. If each target chosen is illegal as that spell or ability tries to resolve, it won’t resolve and none of its effects happen. You won’t create any Junk tokens.

You may pay the squad cost any number of times. You will create a token that is a copy of that permanent for each time you paid the squad cost. If you paid the squad cost multiple times, the tokens will all enter the battlefield simultaneously.

If the spell is countered, the squad ability will not trigger, and no tokens will be created.

If the spell resolves but the creature with squad leaves the battlefield before its squad ability resolves, you’ll still create the token copies.

The tokens created by the squad ability aren’t “cast,” so any abilities that trigger when a spell is cast won’t trigger for the copies.

If, for some reason, the creature doesn’t have the squad ability when it’s on the battlefield, the ability won’t trigger, even if you’ve paid the squad cost one or more times.