The same recommendations as for A/B testing campaign. Optimize your campaign for "App Installs". Define your conversion attribution windows before running a campaign - it ensures that all conversions are tracked in the same, known way. You can track your results through Facebook SDK or any Mobile Measurement Partner.
Bidding, budgeting and optimization approach
Now we recommend to use manual bids. Bidding on Conversions will most likely bring you the best campaign results, as Facebook will deliver your ads to people who are most interested in your offer. You can tell Facebook how much you're willing to pay for a conversion - use CPIs from your A/B testing campaign as a maximum and minimum bids. To get the maximum number of installs for the best price use Leadza Bid Optimization Tool.
Leadza Bid Optimization Tool continuously changes bids every 24 hours within each active ad set such so that the expected number of future installs is maximized. If CPI in any ad set is higher than maximum goal CPI than Leadza Bid Optimization Tool will lower bid the next day, if CPI is lower than minimum goal CPI than Leadza Bid Optimization Tool will increase bid the next day. The tool makes the forecast of key metrics in each ad set on the next day, and it takes into account when deciding how to change bids.
Example of the bidding strategy: