What should you certainly read?

If you are a new user of ADF, and no basis set expert, your primary interests should be in the advice what basis sets you should use and in studying some of the tables which summarize the quality of the new basis sets for a wide variety of diatomic molecules. This will give you an idea of what accuracy you can expect.

For people who have used ADF before, it is highly recommended to study which basis set files have been modified. In case you have performed calculations in which the basis set quality was very important it may be advisable to repeat some calculations with the improved basis sets in order to check that this does not influence your conclusions. This is only needed in case the basis sets you used have been substantially modified. Especially calculations on molecules containing P, Li, Be, K, or Ca, (or the heavier atoms Rb, Sr, Cs, Ba, Fr, Ra) atoms deserve careful attention.

Names of the standard basis sets have changed to more intuitive names: I→SZ, II→DZ, III→DZP, IV→TZP, V→TZ2P, and VI→ET-QZ3P.

Only for basis set experts or users with very specific demands on their basis sets, the description of the basis set utilities is of interest.