SLIME not starting properly on MacOS Emacs

Question

Pretty new to Emacs && Lisp, trying to get started....

I'm trying to get SBCL working via SLIME in Emacs 27.1 (9.0). After following the instructions to add the MELPA repo to my .emacs and installing slime from there, my .emacs looks like this:

(require 'package)
(add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/") t)
;; Comment/uncomment this line to enable MELPA Stable if desired.  See `package-archive-priorities`
;; and `package-pinned-packages`. Most users will not need or want to do this.
;;(add-to-list 'package-archives '("melpa-stable" . "https://stable.melpa.org/packages/") t)
(package-initialize)

(custom-set-variables
 ;; custom-set-variables was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 '(inhibit-startup-echo-area-message "")
 '(inhibit-startup-screen t)
 '(package-selected-packages '(slime)))
(custom-set-faces
 ;; custom-set-faces was added by Custom.
 ;; If you edit it by hand, you could mess it up, so be careful.
 ;; Your init file should contain only one such instance.
 ;; If there is more than one, they won't work right.
 )
(setq inferior-lisp-program "/opt/local/bin/sbcl" )

SBCL in this case is v. 2.0.7, installed from MacPorts.

After starting emacs and running the MELPA package install for slime, I restart Emacs and run:

M-x slime

Which produces a few pages of compiler messages (looks like), ending with:

 wrote /Users/jeff/.slime/fasl/2.26/sbcl-2.0.7-darwin-x86-64/contrib/swank-quicklisp.fasl
; compilation finished in 0:00:00.002

debugger invoked on a SB-BSD-SOCKETS:SOCKET-ERROR in thread
#<THREAD "main thread" RUNNING {10009F8083}>:
  Socket error in "bind": 49 (Can't assign requested address)

Type HELP for debugger help, or (SB-EXT:EXIT) to exit from SBCL.

restarts (invokable by number or by possibly-abbreviated name):
  0: [USE-VALUE] Try a port other than 0
  1: [ABORT    ] Exit debugger, returning to top level.

(SB-BSD-SOCKETS:SOCKET-ERROR "bind" 49)
   error finding frame source: Bogus form-number: the source file has probably
                               changed too much to cope with.
   source: NIL
0] 

This looks to me like some kind of local process is to be started inside the SBCL...interpreter?...VM?..not sure about terminology here; and wants to call back into emacs via a network port, which it cannot seem to bind to, or find. Any ideas?

Thanks so much for the help!