Use token query param not Authorization header. Ensure URL has "download" in it. Creating an API token is at the bottom of Account Settings.
Curl
curl -Lo add-detail-xl.safetensors https://civitai.com/api/download/models/135867?token=$CIVIT_TOKENWget
wget -O add-detail-xl.safetensors https://civitai.com/api/download/models/135867?token=$CIVIT_TOKENAria2
aria2c -o add-detail-xl.safetensors https://civitai.com/api/download/models/135867?token=$CIVIT_TOKEN(used Detail Tweaker XL LoRA as an example)