after redirect you will get id_token and access_token in the redirected url , to create or authenticate user in strapi hit below api with access_token
localhost:1337/api/auth/auth0/callback?access_token=eyJhbGciOiJkaXIiLCJlbmMiOiJBMjU2R0NNIiwiaXNzIjoiaHR0cHM6Ly9wcmVmbGV0LmV1LmF1dGgwLmNvbS8ifQ…0ip_tzWwu7Xd1ESU.yLAYVuuIl3WRMjifgLnvs6ff5DBKZSSCFvLc1HzLAg6l32UHF-RnkLNinYnfkFK56yaUIu35K9E1nu0mrRg5NS7bMU63p7s8alZsJcHDvkZqKvRKxe-PXxPpcT0vSJXxu4XEVGoLwG86G4aWegT818KZgcWE4oethAwThawSLbH17U0VYZ-VvRX6T8NcuXtNYSLitZoLt8UsK1mVXeWLOtX9N0wdHk6DA2fhLQe1_2MBGuAXQmAtTNhNMMF16meESznjO_B7mQ.H9cd8k5uXanT63i247e6EA
it will create user at strapi side and return bearer token.
for login also do the same