What is preventing the replacement engine from starting?

We need to start with where this engine came from. Did you get it out of a running vehicle? Meaning was it running before you installed it? Or is this a new engine?

However, we need air, fuel, spark, and compression to start an engine so we are going to have to go through this to find what we don't have.

https://www.2carpros.com/articles/car-cranks-but-wont-start

We need to check fuel pressure or use starter fluid to check for a fuel issue.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Then we need to pull a spark plug and hold it against the block to see if we have spark.

If we have fuel and spark then we may have a timing issue or other compression issue so we need to check that.

https://www.2carpros.com/articles/how-to-test-engine-compression

Please let us know what you find with this and we can go from there. Thanks