Genome is not enough.
Turns out that acquired traits can be heritable to an extent. Epigenetic structures control expression of genes (basically switch them on and off), making temporary adaptations heritable, but also set initial conditions for the growth of zygote. Without this epigenetic information, zygote will not develop properly.
In animals giving live birth, condition of mother can have huge impact on development of foetus. Incorrect hormonal balance can even lead to foetus developing opposite phenotypical (what it looks and how is built) sex than is coded by genome. Even in case of animals developing inside eggs, proper care is important. Without right amount of heat, egg will not develop. In case of crocodiles, temperature is what decides what sex the hatchling will develop as.
Unless the message codes for all the information, including epigenetics and external or womb-analogue conditions, you won't get much progress. Artificial womb or not.
But there's one another importatn question: should they try to build an alien?
NO! BECAUSE THIS IS AN INVASION!
Interstellar distances are massive. Transferring any materials requires prohibitive energy budget. Same limits don't apply to information. Why then bother sending colony ships, if you could dupe local not-very-intelligent species into building colonists on site? Engineer life form with instinctive knowledge of either genetic engineering or stargate tech. Add extreme breeding rate and either high aggressiveness when not in easily visible captivity or penchant for sneakiness. Send them to the destination, hoping that aborigines will build your engineered life forms. Count on aborigines to teach what they assume are your brethren how their civilisation works, language at the least. Have lifeforms escape and either secretly build stargate beachhead for real invasion, or start building real members of your species (use brain uploading techniques to send mind data to be downloaded into such built blanks). Take over planet. Dispose of aborigines. Dispose of invasion life forms. Dispose of local ecosystem. Install own ecosystem and biochemistry.
Enjoy your new planet, from which you personally will never have any benefit, and which you will never visit. But at the very least, death of your own star, or any other cataclysm will not threaten your species any more.