You bid for me on eBay and I set a high upper limit which I believe was the only bid you entered.
The instructions you give are ambiguous in section (2) and I am confused I.e. "it will snipe the exact price you set" and "you will win at the lowest possible price" Which is true.
Does it enter only one bid and that is the maximum you set.
OR
does it look at the other bids and at the last second calculate what bid within your set range and below or at your maximum is necessary to bid for you to win?
Thnks for your answer.

Please re-read the original message. I think you are confusing "bid" and "win", these are not the same. Your win price could be lower than your bid amount.

The sniper will bid the amount you set. If nobody bid higher, you will win at the lowest possible price just enough to outbid the previous bidder by one increment only.

So just a clarification for this please.

Lets say I put my snipe bid to 90$ in the last 5 seconds.

If before the last 5 seconds, the highest bid was 81$, would this app place a bid of 82$ or 90$?

And last question, would putting 3 seconds before ending, improve the chances of winning (if lets say someone else uses this app), or do I risk if the connection is slow, to not place a bid at all?

The sniper will place $90, but you will win it at $81.

Different time does not improve any chances. Your snipe amount does.
If someone else snipe the same item for $100, you will lose no matter if you set 3 seconds or 10 seconds because your snipe was $90 which is lower.