1. Determine the voltage needed - The power supply needs to be able to supply a little higher than the voltage of your battery bank when it is fully charged.  This is about 7.35% higher for LiFePO4.  The typical charged voltage of a 12.6V LiFeP04 is about 13.6V so you would need a charger capable of at least 14.6V.   Keep in mind there is a difference between marketing speak vs actual needed.  The market refers to battery systems as 12V, 24V, 36V and 48V, but the actual voltages needed are 14.6V, 29.2V, 43.8V and 58.4V for LiFePO4.  Each power supply series offers different sized models so read the correct datasheet on the maximum voltage to make sure it covers the needed charging voltage. The Coltek AE-3000 series have models that offer output voltage at 12V, 15V, 24V, 30V, 36V, 48V and 60V, whereas the GZN-3000 series have models with voltage output of 12V, 24V, 36V, 48V,  60V and 220V.  Notice different manufacturers can have different voltage offerings.  For example, if you have a "24V" battery system (29.2V charging voltage), the only models that meet the voltage requirement would be the 30V, 36V, 48V and 60V for the Coltek AE-3000 series and 36V, 48V, 60V and 220V for the GZN-3000 series.

2. Determine the charging current needed- Batteries have a recommended charging current limit.  This limit is different for different manufacturers.  It is partly determined by the expected battery life.  Higher charging rates can have a negative effect on battery life.  Typically for LiFePO4, the maximum charging current should be no more than the capacity or 1C.  But for maximize battery life, it is better to charge between 0.1C to 0.2C or 10 to 20% of capacity.  So if you have a battery bank with a capacity of 200Ah, charging it between 20A and 40A is way better than 200 amps.  Difference is it will take about 5 to 10 times longer so you need to figure out how that fits your schedule and what you are willing to compromise on. Once you determined the maximum charging current, you will need to check the datasheets to pick one that can supply the maximum charging current AND charging voltage.  A power supply's model name is usually marketed as total power output.  A 3000 series power supply will have models at about 3000W, so a model with a rated current of 250A will have a output voltage of 12V(3000/250).   For the Coltek AE-3000 series, the corresponding rated current are 250A, 200A, 125A, 100A, 83.5A, 62.5A, and 50A, and for the GZN-3000 series, the rated current are 180A, 125A, 83.3A, 62.5A, 50A, and 13.6A.  Note, despite its series name, the 12V model is only 2700W, not 3000W so the rated current is lower.  This is why it's important to check the datasheet and not rely on the name.  So for a "24V" battery system with 200Ah capacity charging at a maximum rate of 0.2C, the Coltek AE-3000 models 30V(100A), 36V(83.5A), 48V(62.5) and 60V(50A) would work, whereas GZN-3000 models that would work are 36V(83.3), 48V(62.5A), and  60V(50A).  Since the 3000W ones may be overkill in this example, Coltek AE series also offers 800W and 1500W series. You would do the same calculations for models with different power ratings. 

One thing to keep in mind in terms of future growth.  If your needs change and you want a faster charge rate (higher C) or you expanded your capacity while keeping the same voltage, then you can add additional power supplies with the output in parallel as long as they have same output voltage.  They can even be from different manufacturers and/or have different current ratings because the current and power will just add together.