Using Ranger's Hail of Thorns spell

I ran a session yesterday (2.23.24) and my ranger was trying to use their Hail of Thorns spell. However, I dont think I understood the proper way to handle this particular spell. I added the spell into the combat tracker under their effects then I had them do the appropiate range attack with their longbow to their assigned target. Their attack was successful but it didnt add the appropiate damage to the target and it didnt have those within 5ft of the target do a saving throw. I didnt have them target the other two creatures nor use 'cast' for the spell.

What is the appropiate way for my ranger to use this particular spell?

In the ranger's effect I had the following in the effects: Hail of Thorns; (C); 'target creatures hit by you with ranged attack and those within 5 ft.

Spells should be added to the characters actions tab and that will automatically add all of the effects required to successfully use the spell. When the spell is cast the user will apply the Hail of Thorns; (C); effect to themselves. This will set up the concentration part of the spell and also create the timer. When the character then wants to use the spell after successfully hitting a target they will then need to target any other targets within 5 feet. Then they'll use the Cast or Save button to force the saving throw on all of the selected targets. The player will then apply the damage by clicking on the damage symbol. Any targets that failed their saving throw will automatically take the full damage and any that succeeded will automatically take half damage.

Zacchaeus,
As always I appreciate the information and I will be using your suggesstion.