Firstly the transaction fee for sending 0.0001
BTC will be more than the amount you will send.
Secondly, everyone is not comfortable with downloading apps not from the official app store. What prevents you from providing a virustotal link at least? If you are not sure what it is, you can upload the full file at
https://virustotal.com/, get it scanned and provide the report url, without which it looks to be fishy.
Thirdly, as a newbie there is little chance anyone will trust you to to the job and get paid. If you are really serious, escrow the funds with someone trusted in this forum.