Robert III, King of Scots died decades before Isabel Stewart of Lorn, Countess of Argyll was born, so that can't be accurate.
Keep in mind that old published genealogies like this book rarely contain any sources and were usually commissioned to help wealthy people in the 1800s establish/invent noble ancestry. Always use them with great caution.
Isabel Stewart of Lorn, Countess of Argyll is my 15th great-grandmother, the daughter of John Stewart, 2nd Lord of Lorn and Agnes MacDonald.
Colin Campbell, 1st Earl of Argyll is my 15th great-grandfather, the so of Archibald Campbell, Master of Campbell and Elizabeth Somerville
PER MY LINE: (Stewarts and Hamiltons)
Margaret Walkup Hamilton her sister → Sir Alexander Hamilton of Haggs, Baronet her father → Alexander Hamilton, 6th of Haggs his father → Helen Dalmahoy his mother → Agnes Hamilton her mother → Sir James Hamilton of Finnart, Kt. her father → James Hamilton, 1st Earl of Arran his father → Mary Stewart, Countess of Arran his mother → James II, King of Scots her father → James I, King of Scotland his father → Robert III, King of Scots his father
To Isabel herself:
Ens. Robert Dunlap, Revolutionary War veteran her father → Capt. Alexander Dunlop his father → Alexander Dunlop, Professor of Greek at Glasgow University his father → William Dunlop, Principal of Glasgow University his father → Elizabeth Mure of Glanderston his mother → William Mure of Glanderstoun her father → William Mure of Glanderstoun his father → Isabel Montgomery his mother → Lady Helen Campbell, of Argyll her mother → Isabel Stewart of Lorn, Countess of Argyll her mother
Isabel Stewart of Lorn, Countess of Argyll is your 15th great grandmother.