These are the methods you can use to earn free cryptocurrency
Eg :
1. AMA(Ask me anything)
2. Testnet
3. Play to earn games
4. Bounty
5. Ambassador Programs
Yeah ambassador and bounty campaign are actually cool ways though but it has became obsolete because especially bounty campaign it doesn't pay a decent amount to the hunters since the project isn't that trusted except for some bounty's that they want to pay hunters with stablecoin like usdt, busd or any other reputable cryptocurrency that can be immediately tradable. There have been series of bounties that launches every single day but doesn't meet up their target if a participant keep doing bounty's without any earning at least $10 to $50 they could get discouraged since no payment is forth coming. Likewise to the ambassadorial program most project pays with their native tokens to their ambassadors, but if talks about mods they are being paid in usdt for their services at least is actually good work on some projects doesn't accept people because of trust issues.
Being a bounty campaign manager is not as lucrative as it has been. Projects are paying way way low compared before where bounty managers receives more than the bounty hunters. Though being a bounty manager today is better than being a bounty hunter since being a bounty manager assures you that you can get something like a pay for your work. It's a good thing that more and more bounty managers are requiring bounty projects to give another coin that has a value, even if it is small, atleast bounty hunters still has an assurance that they can get something from their work.