In the current source downloaded from GitHub - org-roam/org-roam: Rudimentary Roam replica with Org-mode (which is v2) doesn’t have org-roam-dailies-capture-today defined.
It does, strangely, have the v1 function org-roam-dailies-find-today aliased to it.
C-h f org-roam-dai<tab> -> org-roam-dailies-find<tab> completed to ... org-roam-dailies-find-today is an alias for ‘org-roam-dailies-goto-today’, which is not defined. Please make a bug report. This function is obsolete since org-roam 2.0; use ‘org-roam-dailies-goto-today’ instead. Not documented.
In fact, there is no function with the preface `org-roam-dailies-’