Dumitru

Please, pay attention to the difference between sounds and sound events, as those are 2 different things

Sounds can be added via a resource pack, sound events can't be added with a resource pack

Equippable component accepts sound events and not sounds

Please use either one of those 2 commands, which will work with your sound
/give @p minecraft:diamond_boots[item_model=frogspawn,minecraft:equippable={slot:feet,model:diamond,equip_sound:{sound_id:"custom.shriek"}}]
/give @p minecraft:diamond_boots[item_model=frogspawn,minecraft:equippable={slot:feet,model:diamond,equip_sound:{sound_id:"custom.shriek", range: 64}}]

Similar, but i have a message that he couldn't connect to the Minecraft services
here is a fragment from launcher's logs that are spammed once in a while: https://pastebin.com/8YPLmtr5 and here is full log https://pastebin.com/pxgP4VAK