When I try to compile Elixir I get 'Uncaught error in rebar_core'

Erlang/OTP 19 [erts-8.3.3] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false]

Eshell V8.3.3  (abort with ^G)

when I try to add the package from erlang solutions on Fedora Latest using dnf package manger.
Failed to synchronize cache for repo 'erlang-solutions', disabling

while compiling the elixir

==> elixir (compile)
warning: behaviour String.Chars is undefined
  lib/calendar/date.ex:504

warning: behaviour Inspect is undefined
  lib/calendar/date.ex:510

warning: behaviour String.Chars is undefined
  lib/calendar/time.ex:420

warning: behaviour Inspect is undefined
  lib/calendar/time.ex:426

warning: behaviour String.Chars is undefined
  lib/calendar/naive_datetime.ex:648

warning: behaviour Inspect is undefined
  lib/calendar/naive_datetime.ex:655

warning: behaviour String.Chars is undefined
  lib/calendar/datetime.ex:473

Compiling lib/agent/server.ex (it's taking more than 5s)
warning: use Dict is deprecated, use the Map module for working with maps or the Keyword module for working with keyword lists
  lib/hash_dict.ex:11